The goal of this proposal is to generate funds to purchase a new Becton Dickinson FACSCALIBUR W/4 Color option and a Facstation to accommodate the increasing demands of the expanding user group at the University of Colorado Health Sciences Center campus. The dominant user group is comprised of faculty members in the Department of Immunology at the University of Colorado School of Medicine. The user group includes the Chair of the Department of Immunology (KH), the Heads of the Rheumatology (WA) and Allergy and Clinical Immunology (BK) Divisions of the Department of Medicine, the Director of the University of Colorado Immunology Transplant Program (RG), the Program Leader in Immunology of the University of Colorado Cancer Center Program in Immunology (DB) the Executive Director (GE) and Research Director of the Barbara Davis Center for Childhood Diabetes (JH), the heads of the Clinical Immunology and Histocompatibitity Lab of the School of Medicine (BF) and the Immunology Core of the University of Colorado Cancer Center (CR) and the Director of the Immunology/Neurology Research lab (CK). The user group also includes the PI's of training grants in Immunology (KH), Rheumatology (WA), Pediatrics (AH) and Diabetes (GE, JH). In total, these training programs support yearly the training of 10 post-doctoral and 6 predoctoral fellows. The major users are recipients at the time of this application of over 2.9 million dollars in yearly direct NIH support. The instrument requested will alleviate the chronic shortage of Flow cytometry services presently provided to the user group by a single EPICS Elite purchased in 1995. The EPICS Elite flow cytometry time has been increasingly dedicated to sorting. The instrument requested will be operated and managed using an existing structure in place at the Barbara Davis Center for Childhood Diabetes. Its acquisition will permit the user group to perform more routine flow cytometry analyses while retaining the potential for other investigators to simultaneously perform cell sorting experiments. User fees will be charged to fund the management and maintenance of the instrument. Although projected usage should provide enough funding, operating costs not covered by these fees will be absorbed by the Barbara Davis Center with funds provided by John Hutton, who is also the Principal Investigator on this proposal and serves as Research Director at the Barbara Davis Center.